Introduction: Steel Centipede

Picture of Steel Centipede

It's Father's day tomorrow, (or maybe yesterday by the time I get this finished) and I need to hook up my three fathers with presents.

Well, I dabble in (amongst other things) steel artwork. I like using reclaimed steel as it is recycling, inexpensive and I get to make some fairly cool stuff! I try to model my animals after the real thing and usually search out a bunch of pictures of the various forms of the animal before building one. Remember this is just a representation, not an anatomically correct model.

These are made from garage door opener chain (same as a bicycle chain, just longer) and some drop off from a metal fabrication shop. I try to collect a box/bag/bucket full of anything I see in quantity. Of course the materials you find will not be identical but the process is the same.

I recommend starting out with the flat one (on the right) and them moving up to the 3D wall climbing model.

Step 1: Tools

Picture of Tools

Tools: You will need the following:

A fully functional Brain - Some of these processes are inherently dangerous. Always use the proper safety precautions and don’t work over your head.
Welder’s protective gear (a shade 10 helmet and gloves at a minimum)
A fire suppression device (AKA garden hose)
A welder – I use my trusty, dusty Miller 135 with a 25% CO2 and 75% Argon mix and .030 wire. I greatly prefer MIG (Metallic Inert Gas) over wire feed (flux cored wire) as the splatter is almost nonexistent and I get more steel for the buck.
A good solid work surface (or a cheesy one and an anvil)
A hammer (AKA a Bingy Bangy!)
An assortment of pliers
A grinder (angle grinder of pneumatic grinder – your choice)
Curved forms such as a roll of tape or coffee can or other such roundness

Optional but helpful tools:
Welding magnet(s)
Small punch(s) (starting punch and/or drive pin punch)
An oxygen & acetylene torch (a propane torch will also work for chain this small)

Step 2: Materials

Picture of Materials

For this project I used:

Bicycle (or garage door opener, or go kart or any other small type) chain
Metal fab shop drop-off. As mentioned earlier, you probably will not find identical material. You can substitute anything your imagination can come up with. Nails are the first thing that pops into my mind, I’m sure you can think of many others.

Step 3: Cut the Bodies to Length

Picture of Cut the Bodies to Length

Decide how long your centipede will be. then cut a length of chain for the body.

I'm building three so I needed three lengths.

Step 4: Finish the Ends (Free Bonus Lesson!)

Picture of Finish the Ends (Free Bonus Lesson!)

In any design, terminations and connections are what draw the eye (Thanks Mr. Belt), so I like to finish the ends of the chain by removing the cut link.

Free bonus lesson! - This is also how you properly shorten a chain!

Grind off the head of the pin.

Align the outer plate of the chain over a hole in your work surface or anvil so when the pin is driven through it will fall through the hole.
Using a starting punch and a hammer, punch out the pin. Be sure to support the outer plate as close to the pin as possible. This will minimize distortion of the chain.

Step 5: Prep Chain for Welding

Picture of Prep Chain for Welding

If you have ever tried to weld a chain before, you probably have noticed they tend to be coated in grease or oil. This makes the MIG welding process tad bit difficult. An easy way around it its to burn off the oil before welding.

Coil up the chain on your heavy duty work surface.

Use your torch to heat up the chain and burn off the oil. You will be left with a light grey coating of ash and a chain ready to weld.

Step 6: Align the Body and Weld It!

Picture of Align the Body and Weld It!

Using your protective gear and welder, set your welder on a low setting and practice on some scrap chain. When you are confident you can weld the chain without burning through then...

Using your curve template (roll of tape, coffee can etc...) set the chain so it resembles your version of a centipede.

If you are going to make the centipede look like it is climbing a wall, leave a straight section in the middle (or wherever you'd like) so you can bend it later.

Using your protective gear and welder, weld the plates of the chain together. I find that if I start in the middle of an inner plate and move to the outer plate, then back toward the other outer plate I burn through less.

If you are having great difficulties, try pulse welding it. Just pull the trigger for a fraction of a second, wait and do it again until you have the chain welded solid on the outside.

Step 7: Bend It If You Dare!

Picture of Bend It If You Dare!

Bending a small chain like this is a bit iffy. You have to heat up the link that will be on the outside of the curve and stretch it. If you try to heat up the entire link, you will collapse the plate on the inside of the curve.

I used my Oxy-Acetylene torch but a propane torch should be hot enough to get the link to glow.

Get a piece of pipe to bend the chain around.

Tack a vertical surface to your work surface to simulate a wall

Only heat one or two links at a time.

Make your bends slowly and gradually - remember, you can always heat it up and bend it some more.

To get a more graceful curve, heat the links where you welded the plates and bend them as well.

Step 8: Preforming the Legs

Picture of Preforming the Legs

The industrial drop off is very, very sharp, I’m OK with that as centipedes are really quite dangerous. When finished, these critters should not be handled by little children, just like the real ones.

I strive to get my models to be semi realistic so I didn't use the legs as I found them as it would have curved the legs inwards too much. What I did was straighten one tip of the curve (crescent?) so the legs would stick out more and give it a wider stance. (No politician jokes please!)

Of course if you are using nails for legs, you’ll have to put a curve into them rather than take it out.

Hold the leg against the edge of the anvil (or heavy duty work surface) with a pair of pliers so there is a small bit of the curve sticking up.

Strike the curve with the hammer (bingy bangy) so it flattens out the curve. If the edge of your work surface leaves a ding in the inner edge of the leg, dress the sharp edge of the work surface with a grinder.

Step 9: Adding the Legs

Picture of Adding the Legs

I alternate the legs left to right in each opening of the chain.

Use a welding magnet to hold the body to the table. Remember to try not to conduct current through the magnet itself, rather conduct it through the work surface.

Using a pair of pliers, hold the straightened tip of the leg through the body, and weld it from the opposite side. I tried to fill the hole in the link completely as it strengthens the body.

Don't worry if you don't get the leg in the exact position. They are quite easy to bend after it is all welded together.

I usually do all of one side first, skipping every other link, then add the legs to the other side.

Step 10: Adding the Head and Tail.

Picture of Adding the Head and Tail.

I cannot distinguish between the head and tail of any centipede. Therefore I;m not too worried about specific nomenclature. Suffice to say that one end is the front, and the other is the back. I figure the straighter end are the tails (stingers in the back), and the outreaching ones are the heads (feelers in the front). I'm sure some of the bug fans out there in instructable land will be able to clarify this for us.

I used the same crescents for the head and tail, I just straightened them out further.

Form your stingers and feelers.

Holding them with a pair of pliers, weld them to the roller at the end of the chain. Add a bit of extra weld as they will be sticking out and are easy to bend or break off. This will also add a bit of visual mass for appearance.

Step 11: Congradulations! You're Finished!

Picture of Congradulations!  You're Finished!

The possibilities for this are only limited by your imagination. Thanks for reading and have fun!


Ninzerbean (author)2009-06-30

What does "�" mean? No one else asked about it. Anyway, would you sell me one of these guys? I sort of have ended up collecting big iron bugs.

bombmaker2 (author)2008-12-29

is that pneumatic grinder from Harbor Freight Tools

recon506 (author)2008-10-06

Hey Mikey, You seem like a good welder, so if you could please give me your opinion on these welds. They were done on a GPS 1/4" steel plate, with a MIG welder at 17 volts, and 200 in/min wire speed. I think the Argon pressure was at 16 PSI. What do you think? (First time welding ever!)

Mikey D (author)recon5062008-10-06

Strange place for a welding seminar... ...but why not. I assume you are just running a bead, slow your wire feed down a tad and spread the bead out a bit as well. You are building up too high a weld. Travel a bit more slowly and weave back and forth with a small pause at the end of each weave and let the puddle burn into the base metal. Hope it helps! Mikey

TheMadScientist (author)2008-09-02

is it possible to use low heat stick welding for this? aside from changing sticks in-between, but if you moved fast enough, as you would have to, I don't see how you'd run out of stick THAT fast... the trick would be just finding a stick that wouldn't burn right through the entire thing. I also had the idea of using a spot welder on the pins of the bike chain to freeze it in place, I will test this theory soon.

Mikey D (author)TheMadScientist2008-09-03

With a small enough rod and low enough current you should be able to stick weld the chain. I do like the spot welding idea but it may be tedious to position each link correctly as you weld them. Great comments! Thanks! Mikey

bonecholampworks (author)2008-08-15

Oh! Awesome!!! These would look so great climbing up a trellis or post in a garden ... (make em' real big, keep scavengers out too maybe!) ;) I want one......or many! (shuffles off to the dump...) Thanks - A+ job! Janice (ah...snails?...hmmm)

Mikey D (author)bonecholampworks2008-08-15

Thanks Bone! My mother in law wants a frog now. (hmmm... as well) :-)

birdmankustomz (author)2008-07-31

Dude, awesome. And congrates, I think you just came up with the name of my band: 'Steel Centipede'. It's gotta good ring to it.

Mikey D (author)birdmankustomz2008-07-31

Excellent! Use it! I want Video! Mikey

twenglish1 (author)2008-07-13

awesome im gonna make one as soon as i get a welder

Mikey D (author)twenglish12008-07-27

Thanks TW! It's a very relaxing, rewarding, stress relieving hobby.

twenglish1 (author)Mikey D2008-07-27

yah i bet, im building a welder and i hope to have it done soon

LinuxH4x0r (author)2008-06-28


Mikey D (author)LinuxH4x0r2008-07-13

Thanks Linux!

LinuxH4x0r (author)Mikey D2008-07-13

Your welcome! I want to make these as soon as I get a welder (hopefully within a year)

jordanboehmjb (author)2008-07-13

I am a police officer in canada. Stealing centipedes is illegal. If you steal a centipede you will be put in jail immediately. I hope this instructable is for educational purposes only.

Mikey D (author)jordanboehmjb2008-07-13

LOL Yes this is for ed purposes only! Here in good 'ol sunny AZ they're pestilence. And aren't you a tad bit out of your jurisdiction?

Cojon (author)2008-06-23

Great instructable, and your centipedes while not exactly entomologically correct are exciting, alien and spiky vicious! Great stuff! Really cool... I'm going to use electrical conduit and form that tubing to the desired crawling centipede body shape, tack weld the tubing rings in place (if necessary), then cut the tubing in half lengthwise, forming two mirror image bodies. Then, doubling the number of legs, I'll connect them in matched pairs. That is the way real centipedes are. I could make the head from several pieces of the body tubing rotated and tack welded to form a ball of sorts. Centipedes are shiny and dark so maybe buff the back and legs to get shiny highlights, spray it with the lacquer color I want, and quickly wipe the paint off the highlighted areas. Then buff again a bit more to bring the shine back up. Then I think I will coat it with several coats of clear lacquer to stop the rust and keep the shine. Thanks for the perfect idea!

Mikey D (author)Cojon2008-06-25

Thanks Cojon! I do take a certain bit of artistic license. Be careful with the conduit, it is galvanized and the fumes are poisonous! do it outside or with a fan behind you. Thanks again! Mikey

Spint (author)2008-06-17

Really cool. +4.5.

Mikey D (author)Spint2008-06-17

Thanks Llama! Llama, llama, duck! Mikey

Spint (author)Mikey D2008-06-19

Do you know me, because I hear that on a daily basis lol. Due to the fact of me living on a llama ranch I have been known as "Llama" since the 6th grade, and that song as without my consent become my themesong lol.

Mikey D (author)Spint2008-06-19

I don't, but I have teenage children and I hear that and the badger song every so often. Mikey

Spint (author)Mikey D2008-06-19

LOL gotta love us teenagers to bring the hipness/annoying songs to a houshold.

Mikey D (author)Spint2008-06-20

Actually... ...I was the one that showed them! LOL! They just keep playing 'em!

Spint (author)Mikey D2008-06-25

Lol good stuff, gotta love the internet age!

duck-lemon (author)Mikey D2008-06-20

did somebody say duck!

kyle.marsh (author)2008-06-19

This, sir, is amazing. I really enjoyed this entire instructable and I'm not at all surprised to hear that you're a teacher -- I was going to complement you on the pleasant tone of the whole thing and thank you for the extra details you provided that really flesh out the project as a learning exercise, and now I'll add to that that you are a credit to your field.

I'm also excited to see a "man in a helmet" here -- I just picked up some old Willson screw-in style welding goggles from E-Bay for the dual purposes of a costume piece and making a pair of IR-pass goggles. The seller shipped with them two very old books on arc-welding. One is the second edition of Welding Processes and Power Sources from the 70's and the other is Modern arc Welding procedure and practice from Hobart Trade School. I can't find a date on it, but I'd guess it's from the early 50's.

I've been reading through that one and it's completely fascinating (like any subject, you learn a little and think "That might be fun" then you learn more and realize how many factors go into doing it properly and you emerge with a heightened respect for those who have mastered the craft). It's very outdated, I'm sure , but it talks about the basics of welding and is really an interesting read. It discusses the carbon arc and metallic arc using bare and coated electrodes and there's a section in the back that introduces this new-fangled method called TIG that shows a lot of promise...kinda makes me want to learn to weld. I'll have to see if I can convince my school's shop guru to teach me some.

As for the centipedes...I don't have my bike with me over the summer, but would it be feasible to leave some of the links unwelded to let your centipede be reconfigurable?

Mikey D (author)kyle.marsh2008-06-20

Thank you Kyle. I also teach welding in the community college and we use the updated verson of those books. Most of the info in your books is still good and some of the illustrations in ours are from the 50's! I love welding and metal fab, we just finished the steel work on a 30 year old chipper shredder for my father in law. As for the reconfigurable centipede... ...great idea. You would have to make sure you only welded the legs to the side plates or the rollers and you'd have it. Thanks again for the positive comments! Mikey

kyle.marsh (author)Mikey D2008-06-20

You deserve them. I'm a computer science student at a tech college right now, but sometimes I really think I should have been an enigneer -- I really need to get myself into the shop. Actually, I came across something that interested me in the Hobart book that I was wondering if you could explain. I just got to a section that explains how the polarity of DC welding current affects the procedure and it said that up to 75% of the heat is produced at the positive side of the arc. Do you know why this is? I never knew that and never thought about the temperature gradient across an arc before. Thanks! ~Kyle

forgesmith (author)kyle.marsh2008-06-20

Between AutoCAD and modeling software, engineering is mostly computer science these days, right? See if you can work in AutoCAD classes, while programming can be done for it (see link), barring the industry radically changing their de-facto standard just being able to use AutoCAD will keep you well fed.

As to the arc, well, on the negative end the electrons are leaving the metal with their energy, on the positive end they're slamming into the metal with that energy. As a quick and dirty visualization glossing over the science and not completely accurate, It's like a full-auto machine gun firing on the same spot of a solid steel target. The gun barrel will get warm, even hot, but that spot on the target is soaking up the kinetic energy of each and every bullet thus it'll get hotter faster.

I hope that gives you a good enough rough idea of what's happening, as the full science version is of course longer, and likely to be considered weirder as well. And if anybody here has an equally simple yet more realistic explanation, go for it.

kyle.marsh (author)forgesmith2008-06-21

Hah! That's almost excatly the same quick and dirty visualization that I came up with before I asked. Good to know school worked :-). Thanks for the advice, too! ~Kyle

Mikey D (author)forgesmith2008-06-20

I think you nailed it! That's why some rods work better electrode positive and some electrode negative. With electrode negative most of the heat will be in the work and you will penetrate better. For thinner material, electrode negative will work better as you will not burn through as easily. And yes, a good abckground in AutoCAD will do you well. You have to learn to draft with a software program (they all do mostly the same thing, some have different features) and you besetting up a good foundation. If you are interested in computer machining, MasterCAM is a good way to go.

forgesmith (author)Mikey D2008-06-20

Umm, psst, you used "electrode negative" for both thick and thin cases, think you meant electrode positive for thin.

Mikey D (author)forgesmith2008-06-20

Yup, you're correct. My mistake; electrode positive for thin. Thanks for the catch! Mikey

kentuckygold (author)2008-06-19

way cool

Mikey D (author)kentuckygold2008-06-19

Thanks KYAu! Mikey

chalky (author)2008-06-17

STOP!.........................................................................................................HAMMER TIME! LOL excellent little set-up you got there buddy

Mikey D (author)chalky2008-06-17

Thanks Chalky!

Artekus (author)2008-06-15

I like this!

Oh, and for me, Hammer = Universal Adjuster :D

Mikey D (author)Artekus2008-06-15

We also refer to them as the "suitable tool" Whenever you read a manual and it tells you to use a suitable tool, that's it! Thanks! Mikey

Artekus (author)Mikey D2008-06-17

Yes, it's strange how hammers strike that amusing chord the world over (hehe I make a pun). I think it must be our evolutionary predeliction to use blunt objects to solve Problems. Also: "The Implement" in thick German/Russian accent :D

JamesRPatrick (author)2008-06-15

Auto dark is a must.

Mikey D (author)JamesRPatrick2008-06-16

What is auto dark?

JamesRPatrick (author)Mikey D2008-06-16

Auto-darkening masks are like transition glasses. You see right through them most of the time, but when you look at the blinding light of the welding spot, they turn dark. Regular welding masks are dark all the time, but you can't see what you're working on until you start welding.

forgesmith (author)JamesRPatrick2008-06-16

Yeah, if transition glasses could go dark in 0.0001 sec! Mikey D, you can get them as replacement helmet lenses or a new helmet w/ one. Basically they're a LCD you look thru. Some are battery powered (often AA), those are theoretically fastest, others have a solar cell, some go to a fixed shade, some are adjustable and can go darker than 10. They take up viewing space, can fit in a modern helmet like yours and give you an old-school 3-1/2" x 1-2/3" view, but no helmet or lid flipping, line it up and get arcing. I've been considering one for awhile, but even the most basic ones in the stores and catalogs are $100 and up last I looked. Not that long ago I saw a replacement fixed-shade solar version at a welding store for over $140. And if you want "a name" and a fancy flame paint job, heh, you can go over $300. For research I checked eBay for "welding helmet." You should too. I just won a brand new one. Plain and smells import but complete, solar cell w/ rechargeable "internal lithium backup battery," clear at 4, adjusts from 9 to 13. Even has twist-knob headband adjustment and sweat pad. Just $25 w/ $11 S&H.; Can't wait for it to get here, looks loads better than the old one I've been trying to learn with. I can always put flames on it later, guess I saved enough to buy some paint.

Mikey D (author)forgesmith2008-06-16

OK I feel like a goof ball, I thought you were referring to either a coating for steel or a filter for the camera. My hood is Auto Dark, we just call them electronic. My wife got it for me about 4 years ago and I love it. She spent way too much money on it - somewhere in the $360 range! It truly is awesome, especially for this fine work where the initial position of the electrode (wire) is critical. I have seen the cheap ones at stores like Harbor Freight for around $60. However I am leery of trusting my eyes to something like that.

forgesmith (author)Mikey D2008-06-16

...which I would have noticed if I had actually looked at the step 1 pic besides it being a 'roll over' comment... ...never mind, nice work, got a welding manual to review, see you later...

JamesRPatrick (author)forgesmith2008-06-16

I was close enough...

About This Instructable




Bio: I teach High School Welding and Video Game Development (currently) and have taught everything in the Industrial Technology area. I also currently teach Welding at ... More »
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